const PAI:f32 = 3.1415926;
fn main() {

    //定义变量
    //定义变量用let ，用mut定义可变变量
    //let name:type = xx;
    //let mut name:type = yy;
    let a:i8 = 1;
    println!("a = {}", a);
    let mut b:i8 = 2;
    println!("b1 = {}", b);
    b = 3;
    println!("b2 = {}", b);

    //变量的隐藏性
    let b:u8 = 4;
    println!("b3 = {}", b);

    //常量
    // const NAME:type = xx;
    println!("PAI = {}", PAI);


}
